Chromosome 5 comprises about 3% by length of the human genome. We propose to construct an arrayed set of yeast artificial chromosome (YAC) clones specific to this chromosome. A library of approximately 3,000 chromosome 5- specific YACs, comprising about five fold coverage of the chromosome, will be constructed. YAC contigs will be derived from part of the 5q23-q33 region of the chromosome using an initial set of five probes from growth factor/receptor genes within this region. End-specific probes will be derived from these initial anchor loci and will be sued to walk outwards within the arrayed YAC library. Sequence tagged sites will be used in conjunction with a novel cDNA enrichment scheme, to select the cDNAs that are encoded by this region in T-cells and to identify novel cDNAs for encoding new growth factors/receptors.